usb: typec: tcpm: Move TCPC to APPLY_RC state during PR_SWAP

When vbus auto discharge is enabled, TCPCI based TCPC transitions
into Attached.SNK/Attached.SRC state. During PR_SWAP, TCPCI based
TCPC would disconnect when partner changes power roles. TCPC has
to be moved APPLY RC state during PR_SWAP. This is done by
ROLE_CONTROL.CC1 != ROLE_CONTROL.CC2 and
POWER_CONTROL.AutodischargeDisconnect is 0. Once the swap sequence
is done, AutoDischargeDisconnect is re-enabled.

Fixes: f321a02caebd ("usb: typec: tcpm: Implement enabling Auto Discharge disconnect support")
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Link: https://lore.kernel.org/r/20210517192112.40934-3-badhri@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index 3551e33..3feaf5d 100644 (file)
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -789,6 +789,19 @@ static int tcpm_enable_auto_vbus_discharge(struct tcpm_port *port, bool enable)
        return ret;
 }
 
+static void tcpm_apply_rc(struct tcpm_port *port)
+{
+       /*
+        * TCPCI: Move to APPLY_RC state to prevent disconnect during PR_SWAP
+        * when Vbus auto discharge on disconnect is enabled.
+        */
+       if (port->tcpc->enable_auto_vbus_discharge && port->tcpc->apply_rc) {
+               tcpm_log(port, "Apply_RC");
+               port->tcpc->apply_rc(port->tcpc, port->cc_req, port->polarity);
+               tcpm_enable_auto_vbus_discharge(port, false);
+       }
+}
+
 /*
  * Determine RP value to set based on maximum current supported
  * by a port if configured as source.
@@ -4469,6 +4482,7 @@ static void run_state_machine(struct tcpm_port *port)
                tcpm_set_state(port, ready_state(port), 0);
                break;
        case PR_SWAP_START:
+               tcpm_apply_rc(port);
                if (port->pwr_role == TYPEC_SOURCE)
                        tcpm_set_state(port, PR_SWAP_SRC_SNK_TRANSITION_OFF,
                                       PD_T_SRC_TRANSITION);
@@ -4508,6 +4522,7 @@ static void run_state_machine(struct tcpm_port *port)
                tcpm_set_state(port, ERROR_RECOVERY, PD_T_PS_SOURCE_ON_PRS);
                break;
        case PR_SWAP_SRC_SNK_SINK_ON:
+               tcpm_enable_auto_vbus_discharge(port, true);
                /* Set the vbus disconnect threshold for implicit contract */
                tcpm_set_auto_vbus_discharge_threshold(port, TYPEC_PWR_MODE_USB, false, VSAFE5V);
                tcpm_set_state(port, SNK_STARTUP, 0);
@@ -4524,6 +4539,7 @@ static void run_state_machine(struct tcpm_port *port)
                               PD_T_PS_SOURCE_OFF);
                break;
        case PR_SWAP_SNK_SRC_SOURCE_ON:
+               tcpm_enable_auto_vbus_discharge(port, true);
                tcpm_set_cc(port, tcpm_rp_cc(port));
                tcpm_set_vbus(port, true);
                /*

diff --git a/include/linux/usb/tcpm.h b/include/linux/usb/tcpm.h
index 42fcfbe..bffc8d3 100644 (file)
--- a/include/linux/usb/tcpm.h
+++ b/include/linux/usb/tcpm.h
@@ -66,6 +66,8 @@ enum tcpm_transmit_type {
  *             For example, some tcpcs may include BC1.2 charger detection
  *             and use that in this case.
  * @set_cc:    Called to set value of CC pins
+ * @apply_rc:  Optional; Needed to move TCPCI based chipset to APPLY_RC state
+ *             as stated by the TCPCI specification.
  * @get_cc:    Called to read current CC pin values
  * @set_polarity:
  *             Called to set polarity
@@ -120,6 +122,8 @@ struct tcpc_dev {
        int (*get_vbus)(struct tcpc_dev *dev);
        int (*get_current_limit)(struct tcpc_dev *dev);
        int (*set_cc)(struct tcpc_dev *dev, enum typec_cc_status cc);
+       int (*apply_rc)(struct tcpc_dev *dev, enum typec_cc_status cc,
+                       enum typec_cc_polarity polarity);
        int (*get_cc)(struct tcpc_dev *dev, enum typec_cc_status *cc1,
                      enum typec_cc_status *cc2);
        int (*set_polarity)(struct tcpc_dev *dev,